The world energy landscape is vast and convoluted. A rapidly growing global population has resulted in an increased need for power production and distribution. Emerging nations, currently undergoing aggressive efforts in industrialization, have decreased energy supply and increased energy prices worldwide. Reliance on the non-renewable energy source fossil fuels such as oil, natural gas, and coal, has led to dangerous levels of greenhouse gas emissions and other air pollutants. In addition, the processes used for obtaining fossil fuels from the environment, such as drilling and strip-mining, can cause significant damage to the surrounding ecosystems.
The development of renewable energy technology is necessary to prevent further fiscal and environmental damage in the face of growing global energy needs. Simple, cost effective, and broad-scope energy alternatives to fossil fuels will give current energy providers efficient alternatives while providing emerging nations safe and cost effective options for future energy infrastructure plans.
Elimination of pathogen, herbicide, pesticide, and other unwanted material has become an enormous problem in soil, air, water (marine and fresh), and municipal systems. An example is polychlorinated biphenyls (PCBs), which were introduced into the environment through disposal of PCB-containing manufacturing products. Uncontrolled PCB dumping until 1977 led to dangerous levels of PCB compounds in water systems, ultimately resulting in plant, animal, and human toxicity.
Current methods for removing contaminants from waste sites include incineration, ultrasonic treatment of aqueous solutions, irradiation, pyrolysis, microbial digestion, and chemical treatment. However, all of these methods have significant drawbacks. Incineration is effective but expensive on a tonnage scale. Incomplete destruction of contaminants can give rise to secondary contaminants, requiring further treatment. Incineration also has the limitation of being useful to treat contaminated liquid and equipment, but not contaminated soil. Ultrasound remediation techniques can treat liquid-based waste, but form intermediates which require further remediation. Irradiation of deoxygenated PCBs with gamma radiation dechlorinates compounds to give inorganic chloride, biphenyl, and a number of indiscriminate and unknown intermediate contaminants. Pyrolytic methods are extremely energy consuming and also yield products which require post-pyrolytic treatment. Microbial decomposition is a form of bioremediation which is highly specific for contaminants, but is slow, and successful bioremediation treatment can require weeks or months.
Remediation methods for liquid samples include filtration, sedimentation, reverse osmosis, forward osmosis, oxidation/reduction processes, electrolysis, thermal radiation, irradiation, pyrolysis, and enzymatic degradation. Drawbacks to the above-mentioned processes are similar to those for traditional solid waste treatment; namely cost effectiveness, high energy consumption, and significant intermediate and by-product formation requiring further remediation.
Photocatalytic oxidation uses a photocatalyst for the destruction of substances in fluids or air. Useful photocatalysts are generally semiconductors with a room temperature band gap energy of about 3.2 eV. When this material is irradiated with photons (hv) having wavelengths less than about 385 nm (UV), the band gap energy is exceeded and electrons (e) are generated through promotion from the valence band to the conduction band which results in the generation of holes (h+). The resulting highly reactive electron-hole pairs have lifetimes in the space-charge region of the photocatalyst that enables participation in chemical reactions, provided recombination events do not occur first. When a Titanium catalyst is used, the mechanism is postulated to follow as below:TiO2+hv→h++e−  [1]H+OH−→.OH  [2]Ti4++e−−Ti3+  [3]Ti3++O2ads→Ti4++O2ads−  [4].OH+pollutant→oxidized pollutant  [5]Undesired Recombination Reaction: h+e−→hv or heat  [6]
Hydroxyl radicals (.OH) and super-oxide ions (O2ads−) are highly reactive species that can readily oxidize volatile organic compounds and aerosols adsorbed on catalyst surfaces. The Titanium-catalyzed process uses additives such as adsorbed oxygen on the surface of the catalyst. This mechanism and process result in the formation of oxygenated degradation by-products.
There is a need for a simple, cost effective process of harnessing the energy in waste material without the generation of intermediates or by-products which require further remediation. The end goal is a process for conversion of waste and other polluted material to useful components or inert substances which can be utilized for energy or other commercial purposes.
It is therefore the object of the present process to provide a process which eliminates oxygenated by-products generated by current remediation processes.
It is further an object of the present process to efficiently and rapidly dissociate waste products without generating intermediates which require further remediation.
It is another object of the present invention to use the products of the process to generate energy.